Tacoma 2006: weird noise at ignition.

I am wondering if anyone has heard of the following problem and/or may know what is going on? When I start the engine (only when cold and only once per day as far as I can tell), there will be a strange shimmy/whine that seems to come from the drivetrain. I originally thought it was the emergency brake creaking some as I would release it fast enough to get them mixed up. But being more patient has showed me that it happens when the engine is cold and without touching the emergency brake. It is a strange creaking sound that seems to come from below the seat, like something going into gear. Kind of like of grinding shift, but again, it happens before touching the gear shift (manual). Anyone heard of this at all, or from this model year in particular? How serious do you think this problem is? I am reluctant to take it to the dealer because it will not happen except on the first ignition of the day, but I will if it is serious enough. Not a horrendous grinding, but I do not like the sound anyway. Any ideas? Or is there another group I could better contact about this? TIA very much, Allen